There are various types of commercial stacker apparatus which stack cartons and other dimensionally stable packaged products in groups for loading into larger cases. The cartons or boxes to be stacked are typically delivered to the stacker apparatus by conveyors.
In the basic upstacker apparatus, the cartons delivered by the conveyor to the stacker apparatus are received and pushed upwardly during the upward stroke of a vertically reciprocating stacking plate. Shiftable catch plates support the cartons during the downward stroke of the stacker plate and permit vertical stacking. However, the basic upstacker apparatus is limited in its speed of operation, and, when operated at its higher speeds tends to be rough in the handling of the cartons.
The progressive tier stacker apparatus is considered to be a high speed stacker and moves a relatively large number of cartons through the stacking chamber during the upward stroke of the vertically reciprocating stacking plate. Catch plates support the cartons during the downward stroke of the stacking plate. An accumulation pusher pushes a standard product length (usually four cartons) from each horizontal row of the carton stack into a case during loading. However, the progressive tier stacker apparatus is also not very gentle with the product during stacking and must be preloaded.